Application of SMA Wire for an Active Steerable Cannula

2013 ◽  
Author(s):  
Bardia Konh ◽  
Mohammad Honarvar ◽  
Parsaoran Hutapea
Keyword(s):  
Solution Procedure ◽  
Design Parameters ◽  
Fe Model ◽  
Stress Strain ◽  
Thermomechanical Characteristics ◽  
Nitinol Wire ◽  
Series Of Experiments ◽  
The One ◽  
Different Levels ◽  
Steerable Cannula

In this article we present the feasibility of using the shape memory alloy (SMA) wires, namely Nitinol, as an actuator for a steerable surgical cannula. A 3D finite element (FE) model of the actuated steerable cannula was then developed in ANSYS to show deflection of the surgical cannula under the actuation force. The behavior of SMAs was simulated by defining the isothermal stress-strain curves using the multi-elasticity capability of ANSYS. The transformation temperatures of the Nitinol wire at different levels of stress were gathered to form the transformation diagram. Using the one-dimensional Brinson model, the isothermal stress-strain response of the wire was obtained. The thermomechanical characteristics of SMAs were also studied completely by a series of experiments performed on the wires. Birth and death method was used in the solution procedure to have the prestrain condition on Nitinol wire prior to the actuation step. A prototype of the actuated steerable cannula was also developed to validate the numerical simulation. Finally a study was done on design parameters affecting the deflection such as Young’s modulus of cannula, SMA diameter and its offset from the neutral axis of the cannula which can be useful in design optimization.

Feasibility of Shape Memory Alloy Wire Actuation for an Active Steerable Cannula

2015 ◽  
Vol 9 (2) ◽  
Author(s):  
Bardia Konh ◽  
Naresh V. Datla ◽  
Parsaoran Hutapea
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Breast Biopsy ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Needle Insertion ◽  
Design Parameters ◽  
Fe Model ◽  
In Series ◽  
Steerable Cannula

Needle insertion is used in many diagnostic and therapeutic percutaneous medical procedures such as brachytherapy, thermal ablations, and breast biopsy. Insufficient accuracy using conventional surgical cannulas motivated researchers to provide actuation forces to the cannula's body for compensating the possible errors of surgeons/physicians. In this study, we present the feasibility of using shape memory alloy (SMA) wires as actuators for an active steerable surgical cannula. A three-dimensional (3D) finite element (FE) model of the active steerable cannula was developed to demonstrate the feasibility of using SMA wires as actuators to bend the surgical cannula. The material characteristics of SMAs were simulated by defining multilinear elastic isothermal stress–strain curves that were generated through a matlab code based on the Brinson model. Rigorous experiments with SMA wires were done to determine the material properties as well as to show the capability of the code to predict a stabilized SMA transformation behavior with sufficient accuracy. In the FE simulation, birth and death method was used to achieve the prestrain condition on SMA wire prior to actuation. This numerical simulation was validated with cannula deflection experiments with developed prototypes of the active cannula. Several design parameters affecting the cannula's deflection such as the cannula's Young's modulus, the SMA's prestrain, and its offset from the neutral axis of the cannula were studied using the FE model. Real-time experiments with different prototypes showed that the quickest response and the maximum deflection were achieved by the cannula with two sections of actuation compared to a single section of actuation. The numerical and experimental studies showed that a highly maneuverable active cannulas can be achieved using the actuation of multiple SMA wires in series.

Differentiation of new coenomorph in context of the Belgard’s ecomorph system development

2017 ◽  
Vol 28 (1-2) ◽  
pp. 28-35 ◽  
Author(s):  
B. A. Baranovski
Keyword(s):  
Environmental Factors ◽  
Plant Species ◽  
Vascular Plants ◽  
Deciduous Forest ◽  
System Development ◽  
Vascular Plant ◽  
Tabular Form ◽  
Ecological Scales ◽  
The One ◽  
Different Levels

Nowadays, bioecological characteristics of species are the basis for flora and vegetation studying on the different levels. Bioecological characteristics of species is required in process of flora studying on the different levels such as biotopes or phytocenoses, floras of particular areas (floras of ecologically homogeneous habitats), and floras of certain territories. Ramensky scale is the one of first detailed ecological scales on plant species ordination in relation to various environmental factors; it developed in 1938 (Ramensky, 1971). A little later (1941), Pogrebnyak’s scale of forest stands was proposed. Ellenberg’s system developed in 1950 (Ellenberg, 1979) and Tsyganov’s system (Tsyganov, 1975) are best known as the systems of ecological scales on vascular plant species; these systems represent of habitat detection by ecotopic ecomorphs of plant species (phytoindication). Basically, the system proposed by Alexander Lyutsianovich Belgard was the one of first system of plant species that identiified ectomorphs in relation to environmental factors. As early as 1950, Belgard developed the tabulated system of ecomorphs using the Latin ecomorphs abbreviation; he also used the terminology proposed in the late 19th century by Dekandol (1956) and Warming (1903), as well as terminology of other authors. The article analyzes the features of Belgard’s system of ecomorphs on vascular plants. It has certain significance and advantages over other systems of ecomorphs. The use of abbreviated Latin names of ecomorphs in tabular form enables the use shortened form of ones. In the working scheme of Belgard’s system of ecomorphs relation of species to environmental factors are represented in the abbreviated Latin alphabetic version (Belgard, 1950). Combined into table, the ecomorphic analysis of plant species within association (ecological certification of species), biotope or area site (water area) gives an explicit pattern on ecological structure of flora within surveyed community, biotope or landscape, and on environmental conditions. Development and application by Belgrard the cenomorphs as «species’ adaptation to phytocenosis as a whole» were completely new in the development of systems of ecomorphs and, in this connection, different coenomorphs were distinguished. Like any concept, the system of ecomorphs by Belgard has the possibility and necessity to be developed and added. Long-time researches and analysis of literature sources allow to propose a new coenomorph in the context of Belgard’s system of ecomorphs development: silvomargoant (species of forest margin, from the Latin words margo – edge, boundary (Dvoretsky, 1976), margo – margin, ad margins silvarum – along the deciduous forest margins). As an example of ecomorphic characterization of species according to the system of ecomorphs by Belgard (when the abbreviated Latin ecomorph names are used in tabular form and the proposed cenomorph is used), it was given the part of the table on vascular plants ecomorphs in the National Nature Park «Orelsky» (Baranovsky et al). The Belgard’s system of ecomorphs is particularly convenient and can be successfully applied to data processing in the ecological analysis of the flora on wide areas with significant species richness, and the proposed ecomorph will be another necessary element in the Belgard’s system of ecomorphs. 

scholarly journals Design, Analysis, and Experiment on a Novel Stick-Slip Piezoelectric Actuator with a Lever Mechanism

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 863 ◽  
Author(s):  
Weiqing Huang ◽  
Mengxin Sun
Keyword(s):  
Piezoelectric Actuator ◽  
Simple Structure ◽  
Fast Response ◽  
Displacement Sensor ◽  
Design Parameters ◽  
The Finite Element Method ◽  
Stick Slip ◽  
Lever Mechanism ◽  
Series Of Experiments ◽  
Stator Design

A piezoelectric actuator using a lever mechanism is designed, fabricated, and tested with the aim of accomplishing long-travel precision linear driving based on the stick-slip principle. The proposed actuator mainly consists of a stator, an adjustment mechanism, a preload mechanism, a base, and a linear guide. The stator design, comprising a piezoelectric stack and a lever mechanism with a long hinge used to increase the displacement of the driving foot, is described. A simplified model of the stator is created. Its design parameters are determined by an analytical model and confirmed using the finite element method. In a series of experiments, a laser displacement sensor is employed to measure the displacement responses of the actuator under the application of different driving signals. The experiment results demonstrate that the velocity of the actuator rises from 0.05 mm/s to 1.8 mm/s with the frequency increasing from 30 Hz to 150 Hz and the voltage increasing from 30 V to 150 V. It is shown that the minimum step distance of the actuator is 0.875 μm. The proposed actuator features large stroke, a simple structure, fast response, and high resolution.

Indications for Preservation Rhinoplasty: Avoiding Complications

2021 ◽  
Vol 37 (01) ◽  
pp. 045-052
Author(s):  
Mario Bazanelli Junqueira Ferraz ◽  
Guilherme Constante Preis Sella
Keyword(s):  
Nasal Bone ◽  
Nasal Dorsum ◽  
Ideal Candidate ◽  
Deviated Nose ◽  
Lateral Osteotomy ◽  
Upper Lateral Cartilage ◽  
High Radix ◽  
The One ◽  
Different Levels ◽  
The Ideal

AbstractNasal dorsal preservation surgery was described more than 100 years ago, but recently has gained prominence. Our objective is to show the surgical technique, the main indications and counterindications, and the complications. It is a technique that does not cause the detachment of the upper lateral cartilage (ULC) from the nasal septum, and has the main following sequence: preparation of the septum and its resection can be at different levels (high or low, i.e., SPAR [septum pyramidal adjustment and repositioning] A or B); preparation of the pyramid; transversal osteotomy; lateral osteotomy(s); and septopyramidal adjustment. The result is a nose with a lower radix than the original, a deprojection of the nasal dorsum tending to maintain its original shape; an increase in the interalar distance (IAD) and enlargement of the nasal middle ⅓; and loss of projection of the nasal tip and roundness of the nostrils. Thus, the ideal candidate is the one who benefits from such side effects, that is: tension nose, that is, high radix with projected dorsum, projected anterior nasal septal angle (ANSA), narrow middle ⅓, narrow IAD, thin nostrils and straight perpendicular plate of the ethmoid (PPE), and, depending on the characteristics, the deviated nose. The counterindications are low radix, irregularities in the nasal dorsum, ANSA lower than rhinion, and a wide middle ⅓. And the main stigmas are: a nose with a very low radix, middle ⅓ enlarged, residual hump, and saddling of the supratip area. Other issues of this technique are: the shape of the radix; the need or not to remove PPE; wide dorsum; irregular dorsum; ANSA lower than rhinion; weak cartilages; long nasal bone; deviated PPE; and obsessive patient. We conclude that this is a great technique for noses with characteristics suitable to it; care must be taken with the stigmas it can cause.

scholarly journals Numerical Analysis of the Perforated Steel Sheets Under Uni-Axial Tensile Force

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 632 ◽  
Author(s):  
Ahmed M. Sayed
Keyword(s):  
Load Capacity ◽  
Tensile Force ◽  
Three Dimensional ◽  
Tensile Load ◽  
Experimental Tests ◽  
Strain Engineering ◽  
Uniaxial Tensile ◽  
Fe Model ◽  
Stress Strain ◽  
Steel Sheets

The perforated steel sheets have many uses, so they should be studied under the influence of the uniaxial tensile load. The presence of these holes in the steel sheets certainly affects the mechanical properties. This paper aims at studying the behavior of the stress-strain engineering relationships of the perforated steel sheets. To achieve this, the three-dimensional finite element (FE) model is mainly designed to investigate the effect of this condition. Experimental tests were carried out on solid specimens to be used in the test of model accuracy of the FE simulation. Simulation testing shows that the FE modeling revealed the ability to calculate the stress-strain engineering relationships of perforated steel sheets. It can be concluded that the effect of a perforated rhombus shape is greater than the others, and perforated square shape has no effect on the stress-strain engineering relationships. The efficiency of the perforated staggered or linearly distribution shapes with the actual net area on the applied loads has the opposite effect, as it reduces the load capacity for all types of perforated shapes. Despite the decrease in load capacity, it improves the properties of the steel sheets.

Study on Constitutive Mode of Three Typical Rocks Based on Triaxial Compression Test

2012 ◽  
Vol 170-173 ◽  
pp. 322-326
Author(s):  
Kui Chen ◽  
Ren Hua Yang ◽  
Tao Xu ◽  
Ya Jing Qi
Keyword(s):  
Residual Strength ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Digital Design ◽  
Peak Strength ◽  
Design Parameters ◽  
Stress Strain ◽  
Red Sandstone ◽  
Constitutive Mode ◽  
Shield Machine

In order to study the relationship between the design parameters of the shield machine and the strength of rock, the behaviours of rocks under the conventional triaxial compression, the complete stress-strain curves under different confining pressures of three typical rocks, i.e. granite, limestone and red sandstone, were taken out for analysis. From the curves, the values of elastic modulus E and Poisson's ratio μ were gained and the relationships between the following parameters were figured out, which are peak strength versus confining pressure, residual strength versus confining pressure, strain at peak strength versus confining pressure, and strain at residual strength versus confining pressure. According to the values and relationships, the complete stress-strain curves were divided into three parts. For each part, a constitutive equation was established by using the strain softening trilinear elastic-brittle-plastic constitutive model, and all the related parameters in the constitutive equations were also presented, which provide a theoretical foundation for the digital design of the cutter head and cutters of Shield machine.

scholarly journals Towards the Construction of Productive Interactions for Social Impact

2021 ◽  
Vol 13 (2) ◽  
pp. 485
Author(s):  
Blanca L. Díaz Mariño ◽  
Frida Carmina Caballero-Rico ◽  
Ramón Ventura Roque Hernández ◽  
José Alberto Ramírez de León ◽  
Daniel Alejandro González-Bandala
Keyword(s):  
Social Impact ◽  
Ecological Systems ◽  
Research Projects ◽  
Structured Interviews ◽  
Government Officials ◽  
Community Members ◽  
Project Duration ◽  
The Social ◽  
The One ◽  
Different Levels

Understanding the value of research for society has become a priority, and several methodologies have been developed to assess the social impact of research. This study aimed to determine how productive interactions are developed during the execution of research projects. A retrospective study was conducted on 33 projects from 1999 to 2020. Semi-structured interviews with the technical managers were conducted to analyze how different actors of the project—researchers, government officials, and civil society and private sector stakeholders—were involved, illustrating how productive interactions occur in specific biodiversity contexts. The results revealed different levels and intensities of productive interactions; on the one hand, three projects involved all actors; eight involved researchers outside the institution; and 25 involved community members. The number of participants ranged from 2 to 37. All research evaluated had a disciplinary orientation. The type and time of interactions with other interested parties depended on the amount of funding, project type, project duration, and, significantly, on the profile of the technical manager. The importance of assessing and valuing productive interactions was identified as a fundamental element in promoting the social impact of research, as well as integrating inter- or multidisciplinary projects that impact the conservation of socio-ecological systems.

Optimal Design of Vibration Absorber Systems Supported by Elastic Base

1991 ◽  
Author(s):  
Hashem Ashrafiuon
Keyword(s):  
Dynamic Models ◽  
Damping Ratio ◽  
Equations Of Motion ◽  
Elastic Base ◽  
Design Parameters ◽  
Primary System ◽  
Vibration Absorbers ◽  
Equivalent Damping ◽  
System Equations ◽  
Different Levels

Abstract This paper presents the effect of foundation flexibility on the optimum design of vibration absorbers. Flexibility of the base is incorporated into the absorber system equations of motion through an equivalent damping ratio and stiffness value in the direction of motion at the connection point. The optimum values of the uncoupled natural frequency and damping ratio of the absorber are determined over a range of excitation frequencies and the primary system damping ratio. The design parameters are computed and compared for the rigid, static, and dynamic models of the base as well as different levels of base flexibility.

Development of a Methodology for Model Testing of Utor Welded Joints of a Vertical Cylindrical Tank

2021 ◽  
pp. 21-27
Author(s):  
D.A. Neganov ◽  
◽  
A.E. Zorin ◽  
O.I. Kolesnikov ◽  
G.V. Nesterov ◽  
...  
Keyword(s):  
Welded Joints ◽  
Strain State ◽  
Welded Joint ◽  
Design Parameters ◽  
Cylindrical Tank ◽  
Stress Strain ◽  
The Real ◽  
Stress Strain State ◽  
Hydraulic Machines ◽  
Wide Range

The methodology of laboratory modeling of the loading of utor welded joint of the tank is presented. The methodology is based on testing of the special design sample. It allows under uniaxial tension on the typical servo-hydraulic machines to reproduce in the zone of a utor welded joint the combined action of bending and shear forces, similar to that which occurs during the operation of a vertical cylindrical tank. To assess the distribution of the stress-strain state in the proposed design of the sample under its loading, the finite element modeling was performed in the ANSYS software package. It showed the fundamental correspondence of the stress distribution in the zone of the utor node in the sample and in the real tank. The experimental studies consisted in carrying out tests for the durability of a series of 16 samples loaded with the maximum force in the cycle, causing the calculated stresses in the zone of the welded utor node in the range of 100–200 % from the maximum permissible ones. The obtained results showed that the maximum loaded zone, where the destruction of the samples occurred, is the near-seam zone of the utor welded joint on the inside of the tank. This corresponds to the statistics of the real tank failures. It is established that the developed methodology ensures the possibility of carrying out correct resource tests of the tank utor welded joints. It is also possible to vary the stress-strain state scheme within a wide range in the area of the utor welded joint by changing the design parameters of the test sample. In compliance with the regulated welding technologies and the absence of unacceptable defects in the welded joint, the utor node has a high resource, which significantly exceeding 50 years of the tank operation.

I. On the volumetric relations of ozone and the action of the electrical discharge on oxygen and other gases

1860 ◽  
Vol 10 ◽  
pp. 427-428 ◽  
Keyword(s):  
Electrical Discharge ◽  
The Other ◽  
Pure Oxygen ◽  
Silent Discharge ◽  
Gaseous Substance ◽  
Series Of Experiments ◽  
The One

This paper contains the full details of the authors’ experiments on the volumetric changes which occur in the formation of ozone. From three distinct series of experiments, performed by different methods, they show that when ozone is formed from pure oxygen by the action of the electrical discharge, a condensation takes place, as had already been announced in a former Note published in the 'Proceedings.’ But the condensation is much greater than the earlier experiments of the authors on the expansion by heat of electrolytic ozone had indicated. It is, in fact, so great, that if the allotropic view of the constitution of ozone be correct, the density of that body, as compared with oxygen, would be represented by a number corresponding to the density of a solid or liquid rather than that of a gaseous substance. This conclusion follows necessarily from the authors’ experiments, unless it be assumed that when ozone comes into contact with such substances as iodine, or a solution of iodide of potassium, one portion of it is changed back into common oxygen, while the remainder enters into combination, and that these portions are so related to one another, that the expansion due to the one is exactly equal to the contraction arising from the other. For the details of the experiments and of the methods of investigation employed, reference must be made to the original paper. The second part of the communication is devoted to the action of the silent discharge and of the electrical spark on other gases. Hydrogen and nitrogen undergo no change of volume when exposed to the action of either form of discharge. Cyanogen is readily decomposed by the spark, but presents so great a resistance to the passage of electricity, that the action of the silent discharge can scarcely be observed. Protoxide of nitrogen is readily attacked by both forms of discharge, with increase of volume and formation of nitrogen and hyponitric acid. Deutoxide of nitrogen exhibits the remarkable example of a gas which, under the action either of the silent discharge or of the spark, undergoes, like oxygen, a diminution of volume. It also is resolved into nitrogen and hyponitric acid. Carbonic oxide has given results of great interest; but the nature of the reaction has been only partially investigated. The silent discharge decomposes this gas with production of a substance of a bronze colour on the positive wire. The spark acts differently, destroying, as in the case of oxygen, the greater part of the contraction produced by the silent discharge. The authors are engaged in the further prosecution of this inquiry.

Sign in / Sign up

Export Citation Format

Share Document